Infer filename from content-disposition or URL

The Content-Disposition inferring is probably a bad idea security wise,
so I am going to remove it.

tests/unittests/test_http_download.c

@@ -0,0 +1,119 @@
+#include <stdarg.h>
+#include <stddef.h>
+#include <setjmp.h>
+#include <cmocka.h>
+#include <stdlib.h>
+#include <string.h>
+#include <glib.h>
+
+#include "config.h"
+
+#include "tools/http_download.h"
+
+typedef struct {
+    char *url;
+    char *filename;
+} url_test_t;
+
+typedef struct {
+    char *header;
+    char *filename;
+} header_test_t;
+
+void http_filename_from_url_td(void **state) {
+    int num_tests = 5;
+    url_test_t tests[] = {
+      (url_test_t){
+        .url = "https://host.test/image.jpeg",
+        .filename = "image.jpeg",
+      },
+      (url_test_t){
+        .url = "https://host.test/images/",
+        .filename = "images",
+      },
+      (url_test_t){
+        .url = "https://host.test/",
+        .filename = "index.html",
+      },
+      (url_test_t){
+        .url = "https://host.test",
+        .filename = "index.html",
+      },
+      (url_test_t){
+        .url = "aesgcm://host.test",
+        .filename = "index.html",
+      },
+    };
+
+    char *filename;
+    for(int i = 0; i < num_tests; i++) {
+      filename = http_filename_from_url(tests[i].url);
+      assert_string_equal(filename, tests[i].filename);
+    }
+}
+
+void http_filename_from_header_td(void **state) {
+    int num_tests = 11;
+    header_test_t tests[] = {
+      (header_test_t){
+        .header = "Content-Disposition: filename=image.jpeg",
+        .filename = "image.jpeg",
+      },
+      (header_test_t){
+        .header = "Content-Disposition:filename=image.jpeg",
+        .filename = "image.jpeg",
+      },
+      (header_test_t){
+        .header = "CoNteNt-DiSpoSItioN: filename=image.jpeg",
+        .filename = "image.jpeg",
+      },
+      (header_test_t){
+        .header = "Content-Disposition: attachment; filename=image.jpeg",
+        .filename = "image.jpeg",
+      },
+      (header_test_t){
+        .header = "Content-Disposition: filename=",
+        .filename = NULL,
+      },
+      (header_test_t){
+        .header = "Content-Disposition: filename=;",
+        .filename = NULL,
+      },
+      (header_test_t){
+        .header = "Content-Disposition: inline",
+        .filename = NULL,
+      },
+      (header_test_t){
+        .header = "Content-Disposition:",
+        .filename = NULL,
+      },
+      (header_test_t){
+        .header = "Last-Modified: Wed, 21 Oct 2015 07:28:00 GMT ",
+        .filename = NULL,
+      },
+      (header_test_t){
+        .header = "",
+        .filename = NULL,
+      },
+      (header_test_t){
+        .header = NULL,
+        .filename = NULL,
+      },
+    };
+
+    char *got_filename;
+    char *exp_filename;
+    char *header;
+    for(int i = 0; i < num_tests; i++) {
+        header = tests[i].header;
+        exp_filename = tests[i].filename;
+
+        got_filename = http_filename_from_header(header);
+
+        if (exp_filename == NULL) {
+            assert_null(got_filename);
+        } else {
+            assert_string_equal(got_filename, exp_filename);
+        }
+    }
+}